HFS, P8 & Linux/Kegs

[phoenyx <phoenyx@texas.net>]

NOTE: This post is kind of long. Please consider
others if quoting it.

Here's some interesting info regarding those HFS
partitions. HFS like Prodos can only access 65536
blocks on a partition. To be able to use more than
32k per volume HFS uses a variable block size. 512k
for 800k disks, 1024k and up depending upon volume
size for hard drives.

After setting up Kegs/Linux with an HFS volume
I noticed a lot of wasted space on the volume. For
instance, a 67 byte finder.data file took up a whole 4k.
So I decided to play around with an older spare HD
and check some different volume sizes for wasted
space.

I partitioned the drive to various sizes, then used a
test file of 13,312 bytes on each partition.

As it turned out there was no difference with volume
sizes under 64meg. Each used a block size of 1024.
the file showed 13k used on the disk.

Volumes sized at 130 meg seem to use 2048 byte
blocks and the test file showed 15k on disk. 2k of
wasted space.

Volume size of 517 meg showed 17k on disk with
4k of wasted space.

Volume size of 1.2 gig showed the file as 20k which
results in 7k of wasted space. Just think, each finder
file in each directory using 20k. sheesh!

This is definately a lot of wasted space for an 8/16 bit
computer. On the MAC this may not be so noticable
with 32 bit files, but II users expect more efficiency
than that.

So this leaves the HFS user with some decisions to
make. Do you partition the drive with smaller volumes
to make it more efficient or waste some space to make
it easier to use? With a large drive this may be a tough
choice. Perhaps the best solution is a 63 meg partition
for applications which may have lots of small files and
directories and divide the rest of the drive into 130 meg
partitions for archives or such. This is the method I've
chosen. While it requires more effort when dealing with
path names it is certainly better than loosing several
megs of data storage.

While testing the HFS with the Kegs emulator I found
a couple of interesting things. Kegs can use a disk
partition for Prodos 8 as well as HFS. This is a little
faster than the standard HD file image method. As long
as you avoid the partition from Linux everything works
fine. The HFS partitions seem to be faster if you set
Linux to ignore the volumes also. This is probably a
little safer too. Now the only thing missing from this
setup is tools to access a P8 partition from Linux.

So with all this in mind, I've reconfigured my Kegs as
follows.
  s7d1 = p8 partition @ 32m
  s7d2 = p8 partition @ 32m
  s7d3 = p8 partition @ 32m
  s7d4 = HFS partition @ 64m
  ... various storage partitions.
  s7d10 - HFS large backup volume.
This leaves me room to load HD images if needed and
I can shrinkit my volumes to the large HFS for backup
and transfer to othe drives.

I only have the large HFS volume visible to Linux for
net downloading and file transfers as a safety precaution.
Kegs does it's own partition handling so you don't really
need to mount the partitions as you do other file systems.
Too bad Kegs doesn't support an MS-Dos partition. I
tried, no luck.

Back to HFS. If you are using it with volumes larger
than 63 meg you might want to check the disk's file
usage.  Smaller volumes result in more usable space
and faster access since less data is read per block.

Phoenyx